(1) Field of the Invention
This invention relates to improvements in hydrogen generators. More specifically, it relates to a pyrolytic hydrogen generator in which a material can be thermally decomposed to generate hydrogen. The invention is particularly suitable for lightweight applications including man portable applications, especially as part of a fuel cell system. The generator can, however, be used in other systems that require hydrogen on demand, such as larger fuel cells, hydrogen engines or gas chromatographs.
(2) Description of the Art
Hydrogen generating systems fall into two broad classes: the generation of hydrogen from liquid or gaseous hydrocarbons, usually referred to as reformation; and hydrogen generation by the decomposition of hydrogen containing compounds. The decomposition of hydrogen containing compounds can be further categorised; firstly, decomposition in the presence of water, referred to as hydrolysis, and secondly, decomposition by heat, referred to as pyrolysis or thermolysis.
The thermal decomposition of chemical hydrides such as amine boranes and metal borohydrides is commonly used as a means for generating hydrogen. Early patents described the decomposition of these compounds to produce hydrogen in a ‘one shot’ non-controllable reactor for use with high energy chemical lasers. Applicant's International Patent Application Publication No. WO 02/18267 describes a pyrolytic hydrogen generator in which ignition at the hydrogen generating elements is controlled by an ignition control system to allow, for example, for successive or simultaneous ignition of individual pellets in a controllable and load responsive manner.
US2005/0142404 details a variety of pyrolytic gas generation systems in which heat generating elements are supported in various arrays.